An officer once visited Gensha and asked, "They speak of our not knowing it while using it all the time. What is this 'it'?"
Gensha looked as if he were not paying attention to the questioner, for he innocently picked up a piece of cake and offered it to the officer to eat.
The latter finished it and repeated the question.
The master said, "There you are ! It is daily made use of and yet you know it not."
--- D. T. Suzuki